A bicycle is usually driven by means of clockwise pedaling. Thus, a driver has to keep a certain posture for a long time while driving the bicycle. Further, leg muscles are concentrated used in a single direction. This makes its exercise effect reduced in terms of the quantity of motion and a feeling of fatigue increased.
Moreover, in case of a slope, although the weight of a driver is inclined behind, the pedaling must move in the clockwise direction. This males the driver feel tired as higher as several times than a flat. Accordingly, there are problems in that lots of load is applied to the leg and the driver loses interest in riding the bicycle.